<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script src="./vue.js"></script>
  <div id="app">
    <p v-if="flag">v-if控制的</p>
    <!-- v-show相当于display:none，性能更好 -->
    <p v-show="flag">v-show控制的</p>
    <button @click=btn>点击按钮</button>
    <hr>
    <div v-if="type === 'A'">优秀</div>
    <div v-else-if="type === 'B'">良好</div>
    <div v-else-if="type === 'C'">一般</div>
    <div v-else>差</div>
  </div>
  <script>
  const vm = new Vue({
    el:'#app',
    data:{
      flag : true,
      type:'A'
    },
    methods:{
     btn() {
       if (this.flag) {
        this.flag = false
       }else {
        this.flag = true
       }
     }
    }
  })
  </script>
</body>
</html>